The purpose of this study is to study the impact of stem cell dose on outcome after autologous transplant.

Following enrollment, patients will be CD34+ stem cell mobilized at the discretion of the treating attending physician with the plerixafor for the achievement of >6 x10^6 CD34+ cells/kg. The patients that fail to mobilize >6 x10^6 CD34+ cells/kg will not be randomized and will subsequently be followed for disease progression and overall survival.. Patients with >6 x10^6 CD34+ cells/kg cryopreserved on study will be admitted to the hospital for planned ASCT. Patients will be randomly infused with either 3-4 x 10^6 CD34+ stem cells/kg or 6-8 x10^6 CD34+ stem cells/kg on d0 per study randomization. The cell dose ranges within the two groups allows variability within aliquots of cells at the time of cryopreservation. Patients will receive standard supportive measures (including: growth factor support post-HDT/ASCT, antimicrobial prophylaxis, red blood cell and platelet transfusion and treatment for neutropenic fever) as per institutional guideline practices.

Inclusion Criteria:

• Age ≥ 18 years old

• Diagnosed with relapsed or refractory de novo DLBCL or follicular lymphoma transformed to DLBCL to one previous line of anthracycline-containing chemotherapy

• KPS ≥ 70

• Complete or partial response by IWG Working Group or ICML Criteria to maximum of one salvage line of chemotherapy without pre-HDT/ASCT salvage radiotherapy.

• Eligible for high-dose therapy and autologous stem-cell rescue

  • Serum creatinine ≤ 1.5 mg/dL, or if creatinine >1.5 mg/dL, calculated creatinine clearance of ≥50 mL/min by 24 hour creatinine clearance or CKD-EPI.
  • Last cycle of most recent salvage therapy within 8 weeks of enrollment

• Total bilirubin < 2.0 mg/dL

  o If Gilbert"s disease is suspected and total bilirubin > 2.0 mg/dL, direct bilirubin must be < 2.0 mg/dL

• Females of childbearing potential and males must agree to use an acceptable form of contraception per institutional practices.

Exclusion Criteria:

• Disease progression by IWG Working Group or ICML Criteria since last therapy
• Prior autologous or allogeneic stem cell transplantation
• HIV infection
• Comorbid condition(s) which, in the opinion of the attending physician and/or MSKCC Principal Investigator, will preclude stem cell mobilization and/or high-dose therapy with autologous stem cell rescue
• Treatment plan that includes post-transplant maintenance therapy
• Salvage therapy that includes involved field radiotherapy